1996 Chrysler LHS - Idle Problem - Please Help

I'm brand new to the Chrysler Forum, and this is my first post. Hopefully, this will help other LHS owners as well. Here's my story...

A few years ago, my uncle sold me his 1996 Chrysler LHS 3.5L V6 for $600. At the time, it had 150k miles on it and was always garage kept, never driven hard, and always taken to a dealer for any maintenance. Right before I bought it, my uncle had put almost $2,000 of work into it to replace all of the motor mounts and fix up the undercarriage.

Last year, it started to give me a lot of issues. The car would shut off while driving. I determined that the crankshaft position sensor was the issue, replaced it, and the problem went away. At the time, the car also had a random overheating issue. I found out that the head gasket had blown and treated the coolant system with head gasket stop leak. During all of this, we had to replace all of the hoses, radiator, water pump, thermostat, and timing belt. There have also been issues with the fuel pump, fuel injectors, and coil pack. Since then, the overheating issue had stopped.

Since last year, there has been an idling issue that we can't seem to figure out. I know it's not the best option, but I've been throwing some money at it with no results to fix the issue. Right now, the car had almost 180k miles on it, and I drive it back and forth on a two-hour drive once a week with no problems. The only issues I'm having right now are when the A/C kicks on (in park, at idle, or at a stop light) RPM's will drop from 1500 down to 600-700 and then fluctuate. Another issue is that the car will "shimmy" to a stop. It feels like you're driving a manual and stalling it out a little if you don't hit the clutch just right. Also when you're in idle or at a stop light (even with the A/C off), it will shake and rock you back a forth a good bit. It runs fine when you're driving it on the highway, it just has issues as lower RPM's.

I've checked for vacuum leaks, cleaned the fuel injectors with sea foam, cleaned the intake with sea foam spray. Throttle body has been cleaned (without taking it apart). All injectors seem to be working properly. Fuel pressure is normal. Compression is good.

One thing that might help, when I first start it in the morning, it starts right up. After that, it takes awhile to start. Maybe 3 or 4 seconds, but it's only when the engine warms up a little.

Some people said that it might be a Camshaft sensor starting to go bad?

The only issues I'm having right now are when the A/C kicks on (in park, at idle, or at a stop light) RPM's will drop from 1500 down to 600-700 and then fluctuate. Another issue is that the car will "shimmy" to a stop. It feels like you're driving a manual and stalling it out a little if you don't hit the clutch just right.

600-700 is the correct idle speed. 1500 is way too fast for an idle speed. You might want to check the idle air control motor. The engine computer directs the IAC motor to open or close as necessary to maintain idle speed.

The jerking to a stop problem sounds like the torque converter lock-up is sticking. When was the last time the trans fluid was changed? Another thing you could consider is replacing the solenoid pack on the transmission. It's not very expensive and fairly easy to do. Google it for more information.

You're getting misfires on cylinder 2 and 6. Check your coil pack to see if the same coil feeds those two cylinders. A coil pack will have three coils, each coil drives the plugs of two cylinders. Also make sure the wires for those cylinders aren't touching each other or something they shouldn't.

The only issues I'm having right now are when the A/C kicks on (in park, at idle, or at a stop light) RPM's will drop from 1500 down to 600-700 and then fluctuate. Another issue is that the car will "shimmy" to a stop. It feels like you're driving a manual and stalling it out a little if you don't hit the clutch just right.

600-700 is the correct idle speed. 1500 is way too fast for an idle speed. You might want to check the idle air control motor. The engine computer directs the IAC motor to open or close as necessary to maintain idle speed.

The jerking to a stop problem sounds like the torque converter lock-up is sticking. When was the last time the trans fluid was changed? Another thing you could consider is replacing the solenoid pack on the transmission. It's not very expensive and fairly easy to do. Google it for more information.

You're getting misfires on cylinder 2 and 6. Check your coil pack to see if the same coil feeds those two cylinders. A coil pack will have three coils, each coil drives the plugs of two cylinders. Also make sure the wires for those cylinders aren't touching each other or something they shouldn't.

Hope it helps.

I appriceate the help. I'll check it out this week and let you know what I find.

The only issues I'm having right now are when the A/C kicks on (in park, at idle, or at a stop light) RPM's will drop from 1500 down to 600-700 and then fluctuate. Another issue is that the car will "shimmy" to a stop. It feels like you're driving a manual and stalling it out a little if you don't hit the clutch just right.

600-700 is the correct idle speed. 1500 is way too fast for an idle speed. You might want to check the idle air control motor. The engine computer directs the IAC motor to open or close as necessary to maintain idle speed.

The jerking to a stop problem sounds like the torque converter lock-up is sticking. When was the last time the trans fluid was changed? Another thing you could consider is replacing the solenoid pack on the transmission. It's not very expensive and fairly easy to do. Google it for more information.

You're getting misfires on cylinder 2 and 6. Check your coil pack to see if the same coil feeds those two cylinders. A coil pack will have three coils, each coil drives the plugs of two cylinders. Also make sure the wires for those cylinders aren't touching each other or something they shouldn't.

Hope it helps.

My guess is that the transmission fluid has rarely been changed. Since I bought it, it's never been changed out for fresh fluid, but it was probably done when it went to a dealer.

Just an update, I checked the coil pack and wires. Everything seems to be good. I went out and purchased new OEM copper spark plugs, pulled the old ones and found wet oil on cylinders 3 and 6. The rest are straight black. Right after replacing the plugs, I took it out for a 20-mile drive with multiple stops and starts and no hard starts.

Also, the transmission solenoid seems to be what's causing the shaking issue. Whenever I'm sitting somewhere, and it starts shaking, I can put it in neutral, and the shaking will go away.